Structural and Electronic Properties of a Mn Oxide Diffusion Barrier Layer Formed by Chemical Vapor Deposition

A diffusion barrier layer of a few nanometers in thickness is required for a Cu/SiO₂ interconnect structure for advanced integrated circuits (ICs). This paper reports a new barrier material and process by chemical vapor deposition (CVD) of a Mn oxide layer using a bis(ethylcyclopentadienyl)manganese precursor. A good adhesion was obtained when the MnO_x layer was deposited below 300°C because of the small amount of carbon inclusion within the layer. The metal-oxide-semiconductor samples of Cu/MnO_x/SiO₂/p-Si showed a very low leakage current of less than 10^-7 A/cm² at 4 MV/cm and a negligible shift of the flat-band voltage after thermal annealing and bias temperature annealing. The obtained results indicated that the CVD-deposited MnO_x is an excellent diffusion barrier layer for advanced ICs.